In conjunction with paper and board manufacture, the webs must be reeled into mill rolls, which are unwound and rewound back into rolls. Equipment employed for reeling up the web into a roll at the end of the papermaking line is called a winder. Conventionally, the winder is located at the end of the papermaking line. If web finishing is performed on the paper machine, the number of required winders is only one, while off-machine finishing of the web in a separate finishing station requires a winder at the ends of both the papermaking line and the finishing line. A winder is also required at slitter stations. The winder typically has one or two support rolls on which the roll to be wound is supportedly rotated. Furthermore, the equipment comprises arrangements for leading the web onto the support roll and devices for removing a full roll and placing a core for the new roll onto the support roll.
In winders having two support rolls, the web is cut after the roll is finished by means of a knife located between the support rolls by actuating the knife to cut the web prior to the nip between the support roll and the roll. The knife may have a length extending over the entire cross-machine width of the web, or alternatively, a short knife can be used that is moved cross-directionally across the width of the web. While a long knife extending over the entire width of the web is difficult to move between the support rolls due to the limited space available, the crosswise moved short knife has disadvantages in that it is slow and results in cutting the web obliquely unless the winder is stopped for the duration of the web cutting operation. In equipment having only one support roll, this cutting method is not applicable, because the tail of the cut web cannot be reliably led into the nip between the support roll and the roll core. Hence for equipment with a single support roll, the web is cut on the surface of the finished roll, whereby the web tail becomes long and must be further shortened. Furthermore, the topmost plies of the finished roll may easily become damaged during the cutting of the web.
To avoid the shortcomings of the above-described cutting methods, a cord cutting device has been developed based on cutting the web by virtue of taking a cord into the nip between the support roll and the paper roll, whereby the cord cuts and severs the web. The cord is arranged to move into the nip between the support roll and the paper roll so that the cord will be trapped between the topmost ply of the roll and next ply underneath, whereby the topmost ply of the roll remains between the support roll and the cutting cord. After the cord has passed the nip and is moved away from the nip on the other side of the nip, the cord tensions the topmost ply of the roll thus cutting it off. After the web is cut, the full roll is removed from above the support roll and a new roll core is brought in the gap between the support rolls. After the web is cut, the rotation of the support roll is braked to full stop and a new core is brought for the new roll. Prior to cutting the web, glue can be sprayed onto that web surface which will face the next to last ply of the roll in order to secure one end of the web to the roll and the other to the core, respectively.
Some of the most serious problems of the cord cutting device are the ill-defined cutting result and torn cut edge. When the cord is taken through the nip, it remains curved, whereby the cord cuts the edges of the web first. Moreover, the cutting point cannot be controlled accurately, because the cutting action is based on severing the web through tightening the cord, whereby the cutting point varies depending on web qualities and web tension. As the web is cut by pulling a relatively thick cord or equivalent noncutting member across the web, the cutting occurs not by neat cutting, but rather, by tearing. For the same reason, the cutting line must be curved, because the web is easiest torn along a line starting from the web edge. Furthermore, it is obvious that this cutting method is ill suited for heavier grades of paper and paperboard.